This invention relates to the field of manufacture of charcoal briquets and other solid fuel compositions in briquet formats of preferred geometric configurations. More particularly this invention relates to to the apparatus useful in the preparation of preferred designs of briquets of dimensional and geometric specifications and configurations to achieve desired lighting and burn characteristics with respect to intended uses, such as barbecue cooking.
The most common example of such fuel compositions are charcoal briquets which comprise comminuted char of various vegetable materials, such as wood, hulls, pits, and other agricultural waste material which is mixed with a binder and rolled, pressed, or otherwise formed into briquets. However, the present invention has application to the manufacture of other solid compositions, such as comminuted wood or organic material, soap, metal ores and the like otherwise rolled, pressed or extruded into pellets, discs, briquets or other shapes.
Charcoal briquets presently available are typically provided in a "pillow" shape which provides for reasonably satisfactory ease of manufacture by the supplier and handling by the consumer. However, little attention has been paid to their burning characteristics as related to their shape. As is well known, such briquets are typically used for cooking on a grill or the like by preparing a multiplicity of briquets in a mounded configuration, igniting their surface by some auxiliary ignition means such as lighter fluid, electric heaters, etc., and waiting until ignition of a significant portion of the briquets has progressed until a majority of the exposed surface is ignited and burning has progressed inwardly toward the interior of the briquet. As burning proceeds inwardly from the surface of the briquet, a gray ash is formed theron. Thus completion of the initial "ignition phase" of burning is identifiable by the formation of such visual ash on the briquet, and is defined herein as the time at which there is 60-75% visual ash formation on the briquets.
Thereafter the ignited briquets are typically spread under a grill or the like for cooking, and they continue to burn with an intense heat throughout a "burn phase". For maximum performance of such briquets it is desirable that the ignition phase be limited in time so that the briquets may be used for cooking without undue delay, and that the burn phase be extended to provide adequate cooking time for the use intended. It is further desirable to obtain such desirable combustion performance in the most efficient manner with respect to the amount of fuel consumed.
There have been very little prior art developments related to design of solid fuel compositions and articles for desired combustion performance. Other than some work on ornamental configuration of fuel briquets, as well as some attempt to improve the geometrical configuration of briquets, such attempts have not provided desired optimal ignition and burning characteristics. The only recently improved configured fuel briquets is the "D"-shaped briquet as disclosed in U.S. Pat. No. 4,496,366, the disclosure of which is incorporated herein by reference.
Whereas other prior art briquets have recognized that the surface area to volume ratio of the briquet may affect ignition and burn characteristics, U.S. Pat. No. 4,496,366 has provided a solid fuel briquet which displays selected ignition and burn characteristics having a preferred "D"-shaped, half-pillow geometric configuration.
Previous processes utilizing cheek plates placed the cheek plates that formed the sides of the briquet on the same press roll as the pocketed roll. As a result, the product formed in the pocketed press roll adhered to the pockets and was difficult to release. The present invention overcomes the problems associated with the various other prior art processes and briquetting presses utilizing pocketed press rollers with cheek plates adhered thereto. See for example U.S. Pat. No. 3,593,378.
Further, prior art apparatus relies upon the compression of the product on the trailing edge of the pocket to force the product out of the forming rolls. The problem of product adhesion sometimes can be corrected by controlling the physical and chemical characteristics of the material to be compressed.